Aluminum hot rolling processes using aqueous lubricant compositions



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I 3,195,332 Patented July 20, 1965 3,195,332 ALUMlNUMl-IOT ROLLINGl'ROCEIiSES USHNG AQUEOUS LUBRICANT COMPOSITIONS Humbert J. Ranauto,Claymont, DeL, assignor to Atlas Chemical Industries, Inc., Wilmington,Del., :1 corporation of Delaware Filed May 8, 1961, Ser. No. 108,264 2Claims. (CI. 72-42 This invention relates to aqueous lubricantcompositions, and in particular, to the use of aqueous dispersions aslubricants for the hot rolling of aluminum.

QSoluble oils, prepared-from mineral oil bases, are currently being usedin the form of about 4 percent-aqueous solutions as lubricants in thehot rolling of aluminum. These oil-containing aqueous solutions have theundesirable property of allowing aluminum oxide to be transferred fromthe aluminum sheets to the rolls and then back to the sheets. Thiscauses the aluminum sheets being rolled to be marked and to have aduller finish. In addition, the mineral oils cause grease streaks on thealuminum sheets. As a result, it is necessary to perform an addi tionaloperation on the aluminum sheets, removal of the aluminum oxide coatingand grease streaks, which adds to the cost of the hot rolling process.

It is'an object of this invention to provide an aqueous compositionwhich is an effective lubricant for the hot rolling of aluminum.

Another object is to provide an aqueous dispersion which has'sufiicientlubricity to avoid aluminum oxide pickup on the rolls during the hotrolling of aluminum.

A further object is to provide an aqueous lubricant composition which iseasily rinsed from aluminum sheets and thereby avoid greasy streakscaused by the mineral oils currently used as lubricants.

A still further object of this invention is to provide an improvedmethod for hot rolling aluminum. I

Other objects and purposes of this'invention will be apparent to thoseskilled in the art from the description which follows.

It has been discovered that aqueous solutions of a polyoxyethyleneimidazoline represented by the formula wherein R is an alkyl or alkenylradical containing from 11 to 20 carbon atoms and x is a number rangingfrom 3 to 19, are effective lubricants for the hot rolling of aluminum.Illustrative of the polyoxyethylene imidazolines which may be used toform aqueous lubricants are those in which R is heptadeecnyl and x is 8;R is heptadecyl and x is 11; R is undecyl and x is l; etc.

The polyoxyethylene imidazolines useful in accordance with thisinvention are polyoxyethylene derivatives having from about 4 to about20 oxyethylene groups per molecule. Polyoxyethylene imidazolinescontaining relatively small amounts of oxyethylene groups have very goodlubricating properties, but as the oxyethylene content decreases, theybecome insoluble in water and are not readily dispersed in water. Sinceit is necessary that the polyoxyethylene imidazolines at least bedispersible in water in order to be useful as an aqueous lubricant, itis generally preferred that the polyoxyethylene imidazolines contain noless than about 4 moles of oxyethylene groups per mole of imidazoline.As the oxyethylene content is increased, the polyoxyethyleneimidazolines become more soluble in water but their lubricatingproperties are correspondingly decreased. Polyoxyethylene imidazolineswhich are readily soluble in water do not exhibit good lubricatingpropcrties, and for this reason, it is generally preferred that theycontain no more than about 20 moles of oxyethylene groups per mole ofimidazoline. For optimum perform ance as a lubricant for aluminum hotrolling processes, it is preferred that the oxyethylene content of thelubricant range from about 8 to about 12 moles per moleof imidazoline.ln'addition, the properties'of a particular polyoxyethylene imidazolinelubricant can be altered by blending therewith a polyoxyethyleneimidazoline having a different oxyethylcne content. In this manner, thedesired lubricating properties for a particular application can beachieved by blending polyoxyethylene imidazolines of differingoxyethylene content. I

The aqueous lubricant compositions of this invention generally containfrom about 0.1 to about 3 weight percent of polyoxyethylene imidazoline.As previously noted, polyoxyethylene imidazolines containing relativelysmall amounts of oxyethylene groups are more difficult to disperse inwater and therefore lesser amounts of these materials may be used in theaqueous composition. Polyoxyethylene imidazolines containing relativelylarge amounts of oxyethylene groups are readily dispersed in water buttheir lubricating properties are not as etfective as those containingfewer oxyethylene. groups, and therefore, greater amounts of thesematerials may be used to obtain the desired lubricity. If less thanabout 0.1 weight percent of the polyoxyethylene imidazoline is present,there is little or no beneficial lubricating effect obtained. Using morethan about 3 weight percent is impractical from a cost standpoint andmay cause excessive lubricity. In some instances, it may be desirable toincorporate a corrosion inhibitor in the aqueous lubricant compositionsof this invention. Any of the conventional corrosion inhibitors may beused. Representative of corrosion inhibitors which may be present in theaqueous lubricants when used in aluminum hot rolling processes-aresodium nitrite (about 0.05 to about 0.1 weight percent), triethanolamine (about 0.1 to about 0.5 weight percent) and morpholine 7 (about0.1 to about 0.5 weight percent).

The aqueous lubricant compositions of this invention are particularlyuseful in aluminum hot rolling processes. The equipment employed for hotrolling aluminum is called a hot-mill." In its simplest form, theessential features are a pair ofoppositely driven cylindrical rollsarranged in a suitable housing so that the roll axes are parallel toeach other and in a position so that one roll is above the other.Working is accomplished by repeatedly passing a hot, aluminum ingotbetween the rolls. The temperature of the ingot usually ranges fromabout 600 F. to about 950 F. Hot-mills are seldom heated by specialmeans, for the rolls become heated by contact with the hot aluminumingot.

In accordance with this invention, the hot-mill rolls are lubricatedwith the aqueous lubricant compositions. The lubricant may be applied toeach roll from a perforated pipe located above or below the roll andextending across the length of the roll. The aqueous lubricant flowingoff the rolls falls into a collecting pit underneath the mill from whichit may be pumped back to the perforated pipe for further lubrication.The lubricant supply is controlled so that the rolls are covered with asubstantial film over their entire surface.

It has been found that the aqueous lubricant compositions of thisinvention have sutficient lubricity to reduce, and in some instances toprevent, aluminum oxide pickup on the rolls. In addition, the aqueouslubricants are easily rinsed from the rolled aluminum sheets, therebyavoiding greasy streaks which are obtained when mineral oil basedlubricants are used. I I

- The objects and purposes of this invention will become more apparentfrom the following illustrative examples.

imidazoline reactant mixture having an I-ICl equivalent of about 410 and10 grains of sodium hydroxide into an autoclave providedwith a stirrerand a coil for circulating heat exchange fluid therein. Flush theautoclave with ethylene oxide gas and close. Heat the charge to about145 C. and slowly add 3426 grams of ethylene oxide. The, rate of addingthe ethylene oxide and the rate of heat exchange are controlled so as tomaintain the temperature at about 145 C. and the pressure between 30 and50 pounds per square inch. After all of the ethylene oxide has beenadded, the reaction is continued at about 145 C. until a total reactiontime of about hours has elapsed. The reaction is substantially completewhen the pressure drops to atmospheric. .The resultant product is aliquid containing about 20 oxyethylene groupsper imidazoline radicalandis readily dispersib'lein water.

Example II Several other polyoxyethylene derivatives of l-hydroxyethyl-Z-heptadecenyl imidazoline having various oxyethylene contentswereprepared in accordance with the process set forth in Example I. Thefollowing compounds were prepared:

A. l-polyoxyethylene (4) Z-heptadecenyl imidazoline B;1'-polyoxyethylene"(8) Z-heptadecenyl imidazoline' C.l-polyoxyethylenetlZ) 2-heptadecenyl imidazoline D. l-polyoxyethylene(20) Z-heptadecenyl imidazoline wherein thenumber in parenthesisrepresents the moles of oxyethylene groups per mol of polyoxyethyleneimidazoline product. Aqueous solubility tests were run on several ofthese polyoxyethylene imidazoline products.

3% D in 1,000 p.p.m. hard WBIEL Example III Compounds A, B. C and D ofExample I] were also tested in the form of 3% by weight aqueousdispersions for their lubricating properties. I They were compared to amineral oil lubricant for their performance as lubricant in a FalexLubricant Tester.

The Falex Lubricant Tester is a well known testing device comprising asteel journal and bearing loaded by a spring gauge micrometer and drivenby a /3 H.P., 290 r.p.m. motor. The test measures bearing load andresulting wear produced by extreme pressure forces under constant speedand temperature. A detailed descriptionof 4 1 the Fulex machine methodmay be found in ASTM-D-2- Section V, Tech. K.

Lubricant compound: Falex failure load (lbs) Mineral oil approx. 500 A2600 B 2600 C 2000 D f 2250 The Falex test indicates that thepolyoxyethylene imidazoline' aqueous dispersions are etfectivelubricants.

Subsequent tests in a;laboratory rolling mill indicated that 0.5 weightpercent aqueous disper'sionsof the polyoxyethylene imidazolines had verygood lubricating properties. x I

Example IV Introduce 285 grams of l-hydroxyethyl-Z-undecyl imidazolineand 1.5 grams of sodium hydroxide into an autoclave provided with astirrer and a coil for circulating heat exchange fluid therein. Flushthe autoclave with ethylene oxide and close. Heat the charge to 145 C.and add, in increments, 396 grams of ethylene oxide. The rate of addingthe ethylene oxide and the rate of heat exchange are controlled so as tomaintain the temperature at about 145 C. and the pressure between 30 andpounds per square'inch. After all of the ethylene oxide has been added,the reaction is continued at about 145 C. until the ethylene oxide isconsumed as indicated by the decrease of pressure to substantiallyatmospheric. product is a liquid containing about 10 oxyethylene groupsper imidazoline radical and is readily dispersible in water. 1.0% byweight aqueous solutions of this product exhibit effective lubricatingproperties in aluminum hot rolling Example V Introduce,386 grams of1-hydroxyethyl-Z-heptadecyl imidazoline and 1.1 grams of sodiumhydroxide into an autoclave provided with a stirrer and a coil forcirculating heat exchange fluid therein. A polyoxyethylene derivative isprepared as in Examples I and IV by adding 220 grams of ethylene oxideto the autoclave. The resultant product is a liquid containing about 6oxyethylene groups-per imidazoline radical and is readily dispersible inwater. 0.5 weight percent aqueous solutions of this product areetfective lubricants for aluminum hot rolling processes.

Example VI Aluminum ingots were heated to about 900 F. and

were rolled in a conventional two roll hot-mil1. During the ltot'rollingprocess the following three materials were tested as aqueous lubricantsat concentrations of 1 weight percent:

l-polyoxyethylene (8) Z-heptadecenyl imidazoline l-polyoxyethylene (l0)Z-heptadecenyl imidazoline l-polyoxyethylene (l2) Z-heptadecenylimidazoline invention, what is claimed is:

1. A method of hot rolling aluminum whichcomprises the steps of heatingan aluminum ingot to a temperature within the range of about 600 F. toabout 950 F. and

The resultant then passing said ingot through the rolls of a hot-millwhile contacting the surface of said ingot with an aqueous lubricantcomposition comprising water and from about 0.1% to about 3% by weightof a polyoxyethylene imidazoline represented by the formula.

H(OCII,Cll1)r-0CII CTI N u 1 j Gin-on, wherein- Ris selected from thegroup consisting of alkyl and al-kenyl radicals which contain'from 11 to20 carbon atoms and x is a numberfrom 3 to 19.

2. The method of claim 1 in which the aqueous lubricant composition alsocontains a corrosion inhibitor.

References Cited by the Examiner UNITED STATES PATENTS DANlEI s WYMAN,Primary Examiner.

JULIUS GREENWALD, Examiner.

1. A METHOD OF HOT ROLLING ALUMINUM WHICH COMPRISES THE STEPS OF HEATINGAN ALUMINUM INGOT TO A TEMPERATURE WITHIN THE RANGE OF ABOUT 600*F. TOABOKUT 950*F. AND THEN PASSING SAID INGOT THROUGH THE ROLLS OF AHOT-MILL WHILE CONTACTING THE SURFACE OF SAID INGOT WITH AN AQUEOUSLUBRICANT COMPOSITION COMPRISING WATER AND FROM ABOUT 0.1% TO ABOKUT 3%BY WEIGHT OF A POLYOXYETHYLENE IMIDAZOLINE REPRESENTED BY THE FORMULA